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The Executive’s Misplaced Reliance on War Powers “Custom”

Published online by Cambridge University Press:  20 January 2017

Michael J. Glennon
Of the Board of Editors


Historical practice, or custom, has long been seen as a source of authority in the resolution of separation-of-powers disputes. In two recent cases assessing the limits to the president’s power regarding the recognition of foreign nations and the making of recess appointments, the Supreme Court heavily emphasized past practice. Historical practice, the Court said, reflects “the compromises and working arrangementsth at the elected branches of Government themselves have reached.” in the realm of war powers, the executive branch has long relied on custom to justify military initiatives that were carried out without congressional approval. In essence, the executive has argued that because force has been used in the past without congressional approval, the same is permissible in various other situations (for example, in the Dominican Republic, Grenada, Haiti, Kosovo, and Panama).

Editorial Comment
Copyright © American Society of International Law 2015

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1 See generally Glennon, Michael J., The use of Custom in Resolving Separation of Powers Disputes, 64 B.U. L. Rev. 109 (1984)Google Scholar. Because custom counts more in some situations than in others, “any examination of historical practice must reckon with the hierarchy of legal sources in... different methodologies,” some of which accord less weight to custom than do others. LaCroix, Alison L, Historical Gloss: A Primer, 126 Harv. L. Rev. F. 75, 81–82 (2013)Google Scholar. I suggest a hierarchy of sources, integrating custom with the constitutional text, case law, Framers’ intent, and functional considerations in Michael J. Glennon, Constitutional Diplomacy (1990).

2 Zivotofsky v. Kerry, No. 13-628 (U.S. June 8, 2015).

3 Nlrb v. Noel Canning, No. 12-1281 (U.S. June 26, 2014).

4 Id., slip op. at 2.

5 See, e.g., Meeker, Leonard, The Legality of United States Participation in the Defense of Viet-Nam, 54 Dep’t St. Bull. 474, 484 (1966)Google Scholar (“Since the Constitution was adopted there have been at least 125 instances in which the President has ordered the armed forces to take action or maintain positions abroad without obtaining prior congressional authorization, starting with the ‘undeclared war’ with France (1798–1800).”) As Meeker pointed out, however, Congress did approve use of force in Vietnam by enacting the Gulf of Tonkin Resolution.

6 See, e.g., Presidential Power to use the Armed Forces Abroad Without Statutory Authorization, 4A Op. Off. Legal Counsel 185, 187 (1980).

7 Memorandum from Caroline D. Krass, Principal Deputy Assistant Attorney General, Office of Legal Counsel, to Eric Holder, Attorney General, Authority to use Military Force in Libya 7 (Apr. 1, 2011), at

8 Id.

9 Id.

10 Remarks on the Situation in Syria, 2013 Daily Comp. Pres. Doc. 596 (Aug. 31, 2013), at

11 Letter to Congressional Leaders Reporting on the Commencement of Military Operations in Iraq, 2014 Daily Comp. Pres. Doc. 650 (Sept. 8, 2014), at

12 With respect to military actions undertaken against Isis, the White House threw in the unconvincing claim that authority is also conferred by preexisting statutory authorization to use military force against al Qaeda (in 2001) and Iraq (in 2002). Ackerman, Spencer, White House Says Expired War Powers Timetable Irrelevant to Isis Campaign, Guardian (Oct. 16, 2014)Google Scholar, at If such authority were in effect, it would conveniently have forestalled the application of the War Powers Resolution’s sixty-day time period. War Powers Resolution, sec. 5(b)(1), Pub. L. No. 93-148, 87 Stat. 555 (1973) (codified at 50 U.S.C. §§1541–1548 (2012)).

13 See Bradley, Curtis & Morrison, Trevor, Historical Gloss and the Separation of Powers, 126 Harv. L. Rev. 411, 439–447 (2012)Google Scholar (describing why the president and Congress are not equally situated in their ability to act).

14 Barbara Salazar Torreon, Congressional Research Service, Instances of use of United States Armed Forces Abroad, 1798–2015 (2015), at

15 See, e.g., Memorandum from Caroline D. Krass, supra note 7.

16 Id.

17 Daalder, Ivo & Stavridis, James, Nato’s Victory in Libya: The Right Way to Run an Intervention, Foreign Aff., Mar.–Apr. 2012, at 2 Google Scholar, 2.

18 U.S. Department of State, Bureau of Counterterrorism, Country Reports on Terrorism 2013, at http://www.

19 Hausloherner, Abigail, Libyan Militia Leader Says Looters Stole Shoulder-Fired Missiles, Wash. Post, Sept. 25, 2012, at A12 Google Scholar.

20 Becker, Elizabeth, U.S. General Was Overruled in Kosovo, N.Y. Times, Sept. 10, 1999, at A6 Google Scholar; see generally Michael J. Glennon, Limits of Law, Prerogatives of Power: Interventionism After Kosovo (2001).

21 Zivotofsky v. Kerry, supra note 2, at 11.

22 Perhaps aware of such considerations, in response to questions from the Boston Globe in 2007, then-Senator Barack Obama gave a well-known answer: “The president does not have power under the Constitution to unilaterally authorize a military attack in a situation that does not involve stopping an actual or imminent threat to the nation.” Savage, Charlie, Barack Obama’s Q & A, Bos. Globe, Dec. 20, 2007 Google Scholar, at

23 See Glennon, Michael J., The Cost of “Empty Words”: A Comment on the Justice Department’s Libya Opinion, Harvard National Security Journal Forum (Apr. 14, 2011)Google Scholar, at; Roberts, Hugh, Who Said Gaddafi Had to Go?, London Rev. Books, Nov. 17, 2011, at 8 Google Scholar; Kuperman, Alan, A Model Humanitarian Intervention?: Reassessing Nato’s Libya Campaign, 38 Int’l L. Security 1 (2013)Google Scholar.

24 Dames & Moorev. Regan, 453 U.S. 654, 669 (1981).Zivotofsky andNoel Canning, like Dames & Moore, suggest that the posture of Congress, and thus the validity of certain presidential action, does not depend solely on for mally enacted legislative measures. The Court seems to have backed off from the formalism of Ins v. Chadha, 462 U.S. 919 (1983), where it held that measures not subject to the president’s veto cannot have the force of law.

25 See Michael J. Glennon, National Security and Double Government (2014).

26 For the classic work on the difficulty of assessing legislative intent, see Radin, Max, Statutory Interpretation, 43 Harv. L. Rev. 863 (1930)CrossRefGoogle Scholar.

27 See generally Morrison, Alan, The Sounds of Silence: The Irrelevance of Congressional Inaction in Separation of Powers Litigation, 81 Geo. Wash. L. Rev. 1211 (2013)Google Scholar.

28 Scholars have identified structural reasons why Congress fails to respond to executive encroachmentson its war powers. For example, getting 535 members to deal coherently with collective-action problems is a challenge. Loyalties to party often trump loyalties to the institution of the House or Senate. Members of Congress often are driven by the electoral connection (that is, the desire to be reelected), which sometimes conflicts with institutional protection. See Bradley & Morrison, supra note 13.

29 Torreon, supra note 14.

30 Nlrb v. Noel Canning, supra note 3, Concurring Op. Scalia, J., slip op. at 26.

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